Pneumatics is often used where the potential dangers of electricity pose too great a risk for electrical power to be used. Equipment used in mines and submerged or standing in water are probably the most prevalent applications.
Back in the days before widespread use of electricity, steam engines were the prime mover of choice, but potential dangers of the firebox of steam engines prevented their use in underground mines. Not surprisingly, pneumatics posed a practical alternative even then.
If you travel to Chandler, Ariz., you can see a sample of this mature technology that is still widely used today in one form or another. Fireless locomotive #3290, displayed at the Arizona Railway Museum, was built by the H. K. Porter & Co. in 1905 and was used by Homestake Mining Co. until it was retired in August 1985. Homestake Mining Co. was one of the largest gold-mining companies from the 1800s until it merged with Canada’s Barrick Gold Corp. in 2002.
The locomotive has a 0-4-0 wheel arrangement, weighs 10,000lb, and its 23-in. drive wheels were designed to produce a tractive effort of 18,600 lb. Rated at 1,000 psi, its receiver fed drive air cylinders, each with a 6-in. bore and 10-in. stroke.
The locomotive was donated by Homestake Mining Co. to the Museum and has been on display at the Arizona Railway Museum since 1997.